1. Field of the Invention
The present invention relates to a ball joint used, for example, at a connection portion of a vehicle stabilizer.
2. Description of the Related Art
Thus type of ball joint is, as disclosed in Japanese Patent Application Laid-Open (JP-A) No. 8-284948, constructed so that a ball portion at one end portion of a ball stud is slidably fitted together with a ball seat and the ball stud is universally pivotably-supported. Furthermore, in order to fix it to a mounting member, the distal end side of the ball stud, at which a screw portion is formed, is passed through the mounting member, and a nut is screwed into the screw portion and fastened. The mounting member is thereby sandwiched by the seat surface portion formed at the ball stud and the nut, and is fastened.
When the nut is fastened and the ball stud is fixed to the mounting member, because the ball stud freely rotates with respect to the ball seat, if the rotation torque of the nut exceeds the frictional resistance of the seat surface portion for the mounting member, co-rotation in which the ball stud co-rotates along with the nut occurs, and fastening cannot be carried out. In a conventional art, a hexagonal head wrench is fitted with a hexagonal socket formed at the distal end surface of the ball stud, and due to the ball stud being regulated, fastening of the nut is possible. However, the fastening work is troublesome and this is unsatisfactory arises. Thus, in the above-described publication, it is proposed that a co-rotation preventing plate, whose area is greater than that of the seat surface, is sandwiched between the seat surface and the mounting member, and the co-rotation is prevented by increasing the frictional resistance with respect to the mounting member by the co-rotation preventing plate.
However, if the co-rotation preventing plate is used, an increase in the number of parts and the troublesomeness of assembly work in accordance therewith are brought about. Furthermore, it is supposed that there are cases in which, in accordance with the state of the degree of surface roughness of the abutting surfaces of the mounting member and the co-rotation preventing plate, the increase in frictional resistance is slight, and co-rotation cannot be reliably prevented.